<!DOCTYPE html> 
<html lang="en"> 
<head> 
<meta charset="UTF-8"> 
<meta name="viewport" content="width=device-width, initial-scale=1.0"> 
<title>示例10</title> 
<script> 
  // 解构默认值 
  let [x, y = 'b'] = ['a']; 
  console.log(x); //'a' 
  console.log(y); //'b' 
  </script>  
 </head> 
 <body></body> 
 </html> 